The present invention relates to a display panel having a protective layer containing transparent beads, and a process for producing the same.
A display panel used in an instrument of an automobile will be described as an example. A first conventional example shown in FIG. 8 comprises a transparent and colorless substrate 1 having formed thereon a white display layer 3 for forming a display part 2 of scales, characters and numerals, and a black opaque layer 4 formed by printing on a part except the display part 2. A transparent protective layer 5 is provided to cover the display part and the opaque layer 4. The protective layer 5 is to protect the printed surface of the display panel and to suppress reflection of outside light upon looking at the display panel. The protective layer 5 is mixed with, for example, a silica series matting agent. In the display panel of this type, the display part 2 looks white on a black background.
A second conventional example will be described where a lamp is provided on the back side of the display part 2, and the display part 2 becomes visible only when the light is turned on. The display panel shown in FIG. 9 comprises a transparent and colorless substrate 1 having thereon a black opaque layer 4 by printing on a part except a display part 2 of scales, characters and numerals. A black translucent colored layer 6 is provided below the opaque layer 4 at the position corresponding to the display part 2. A transparent protective layer 5 is provided to cover the translucent colored layer 6 and the opaque layer 4. The protective layer 5 is the same as that in the first conventional example. A red colored transparent layer 7 is printed on the back surface of the substrate 1 corresponding to the display part 2.
In the display panel of the second conventional example, the display part 2 of characters and symbols becomes visible only when the lamp provided on the back side of the display part 2 is turned on, and upon turning off the lamp, the presence of the display part 2 is difficult to recognize because both the display part 2 and the part other than display part 2 (the part where the opaque layer 4 is provided) are black.
However, while a silica series matting agent, for example, is mixed in the protective layer 5 for suppressing reflection of outside light in the first conventional example as described in the foregoing, since the matting agent of this type has an opacifying power, the transparency is somewhat lowered after providing the protective layer 5, and the surface of the display panel becomes slightly whitish, whereby sophisticated feeling is impaired. Furthermore, a step H formed by printing appears around the display part 2 to make the appearance unattractive. The step H formed by printing becomes conspicuous in the case where the display layer 3 and the opaque layer 4 provided on the front surface of the display panel are formed with an ultraviolet ray curable ink rather than the case where they are formed with a solvent ink. This is because in the case of a solvent ink, a solvent contained in the ink is evaporated by drying after printing, and the film thickness of the ink becomes small as a result, whereby the step is not conspicuous in comparison to the case using the ultraviolet ray curable ink.
The case of the second conventional example involves the same problem as in the first conventional example, and in the case where the display part 2 is a warning indicator, there is another problem in that forefeel of something is caused at the display part 2 by the step H formed by printing, whereby the warning effect as a warning display is sometimes attenuated. As a third conventional example for solving the problems, a display panel shown in FIG. 10 comprises a substrate 1 having formed on the back surface thereof a red colored transparent layer 7, and a black opaque layer 4 is formed by printing at the part other than a display part 2 of characters and symbols. A black translucent colored layer 6 is formed on the front surface of the substrate 1, and a transparent protective layer 5 is formed to cover the translucent colored layer 6.
In the display panel of the third conventional example thus constituted, the display part 2 of characters and symbols is displayed by transmission in red only on turning on the lamp as similar to the second conventional example, and on turning off the lamp, the presence of the display part 2 is not recognized because the display part 2 and the part other than the display part 2 are flat, and they are covered with the black translucent colored layer 6. Accordingly, the third conventional example has no step formed by printing on the front surface of the substrate 1, whereby it has no unattractive appearance and exhibits a warning effect as a warning display. However, because the position where the display part 2 is formed is the back side of the substrate 1, the contour of the display part 2 is blurred owing to the thickness of the substrate 1, and the display part 2 is not clearly displayed by transmission. The phenomenon becomes considerable when the substrate 1 is thick.
An object of the invention is to provide a display panel having a sophisticated appearance, having no conspicuous step formed by printing, and exhibiting clear display of a display part on transmitted illumination to make the visibility good, and a process for producing the same.
The invention relates to, as one aspect, a display panel comprising a substrate; a display layer for forming a display part formed on a front side or a back side of the substrate; a background color layer formed on a part except the display part; and a transparent protective layer containing transparent beads oriented on the front side, provided on the front side of the substrate. According to the display panel of this aspect of the invention, outside light is diffusely reflected to make a matte state, and the background color is clearly reproduced since the resin beads are transparent, whereby a sophisticated appearance is obtained. Furthermore, a step formed by printing is not conspicuous even when the display part is formed on the front side of the substrate, to attenuate an unattractive appearance and to increase sophisticated feeling.
The present invention also relates to, as another aspect, a process for producing a display panel comprising the steps of: providing a display layer for forming a display part on a front side or a back side of a substrate; providing a background color layer on a part except the display part; providing a transparent protective layer containing transparent beads on the front side of the substrate; and heating the display panel after providing the protective layer. According to the process for producing a display panel of this aspect of the invention, the transparent resin beads can be oriented on the front side of the protective layer by a simple procedure containing only heating the display panel after providing the protective layer.
The present invention also relates to, as a further aspect, a display panel comprising a substrate; an opaque layer formed on a front side of the substrate at a position other than a display part; a translucent colored layer having a color that is the same as or approximate to a color of the opaque layer on the front side or a back side of the substrate at least at a position corresponding to the display part; and a protective layer containing transparent beads oriented to the front side, provided above the display part and the opaque layer. According to the display panel of this aspect of the invention, outside light is diffusely reflected to make a matte state, and a step formed by printing is not conspicuous even when the display part is provided on the front side of the substrate, whereby the presence of the display part becomes difficult to recognize. The contour of the display part is not blurred, but the display part is clearly displayed by transmission to obtain a display panel having good visibility. The background color is clearly reproduced since the resin beads are transparent, and thus sophisticated feeling can be obtained.
In a preferred embodiment of this aspect of the invention, the translucent colored layer is provided above the display part and the opaque layer, whereby there is no difference in gloss between the display part and the opaque layer, and the presence of the display part on turning off the lamp becomes further difficult to recognize.
In another preferred embodiment of this aspect of the invention, a transparent colored layer is provided below the translucent colored layer at a position corresponding to the display part, whereby the warning effect as a warning indicator is further improved.
In a further preferred embodiment of this aspect of the invention, the layers provided on the front side and the back side of the substrate each comprises an ultraviolet ray curable ink, whereby a step formed by printing can be inconspicuous even when an ultraviolet ray curable ink forming a large thickness, and since it exhibits quick drying property and high surface hardness, the printing working property and the flaw resistance becomes better.
The invention also relates to, as a still further aspect, a process for producing a display panel comprising the steps of: providing an opaque layer on a front side of a substrate except a display part; providing a translucent colored layer having a color that is the same as or approximate to a color of the opaque layer on the front side or a back side of the substrate at least at a position corresponding to the display part; providing a protective layer containing transparent beads above the display part and the opaque layer; and heating the display panel after providing the protective layer. According to the process for producing a display panel of this aspect of the invention, the transparent resin beads can be oriented on the front side of the protective layer by a simple procedure containing only heating the display panel after providing the protective layer.